Keep-alive cones and method of making same



July 16, 1963 J. H. BURTHE ETAL 3,

KEEP-ALIVE CONES AND METHOD OF MAKING SAME Filed Nov. 24, 1961 i m m 2% M W32 2 NH? 0 5% U mwkw A 2 a my? w United States Patent 3,098,172 KEEP-ALIVE CONES AND METHOD OF MAKING SAME Jack H. Burthe, North Linthicum, Irvin John Kenner, Baltimore, and James D. Woermbke, Linthicum, Md, assignors, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Filed Nov. 24, 1961, Ser. No. 154,912 6 Claims. (Cl. 315-58) The present invention relates to a keep-alive cone and the method of making same. A keep-alive cone is normally provided in the crystal protector stage of a radar duplexer for the purpose of maintaining a copious supply of free electrons in the interaction gap of this stage. By having an abundance of electrons, ionization of the gas within the tube is easily initiated by the application of RF power. Firing and leakage power, along with spike leakage energy, are directly affected by the initial electron density in the interaction gap.

As loss of the keep-alive discharge will result in the destruction of the detector crystals, and consequently, a complete failure of the radar gear, it is highly important that keep alive cones be electrically stable and mechanically strong. Heretofore, one problem encountered with keep-alive cones was the shorting of the center conductor to the outside metallic cone during periods of shock and vibration.

In the present invention, the center conductor is positioned within .a metallic cone by an electrical insulator which is used for stabilizing the glow discharge. All parts are machined so that they are self-jigging. After the center conductor has been placed in position, powdered glass is used to fill the void within the cone, and the assembled unit is then heated at 1050 degrees C. for one and one-half minutes. The heat melts the powdered glass and upon cooling the glass is fused to the center conductor and metallic cone resulting in a rugged vacuum band of the complete assembly. A series resistor is attached to the portion of the center conductor that protrudes above the glass seal and this resistor and the remaining portion of the center conductor are potted with an epoxy resin. The completed assembly is both electrically stable and mechanically strong and will not short when subjected to severe shock and vibration.

It is therefore a general object of the present invention to provide an improved keep-alive cone for protecting the detector crystals in a radar duplexer.

Another object of the present invention is to provide a keep-alive cone that is electrically stable, mechanically strong and easily fabricated.

Other objects and advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing wherein:

FIGURE 1 is a top view showing the present invention, and

FIGURE 2 is a sectional view taken on lines 2-2 of FIGURE 1.

Referring now to the drawing, there is shown a housing or cone 11 that is provided with a plurality of stepped cavities and an aperture 12. A stepped insulator 13 is provided in the cavities and-a reduced diameter portion 14 of a center conductor is supported in the bore of insulator 13. Cone 11 and center conductor are made of a glass sealing alloy, such as Kovar.

A part of the enlarged diameter portion 16 of the center conductor is surrounded by an enlarged cavity in cone 11, and this enlarged diameter portion 16 is glasssealed to cone 11. A part of enlarged diameter portion 16 extends above the top surface of cone 11 and this 3,098,172 Patented July 16, 1963 "ice 2 portion is enclosed by potting with a thermosetting resin, such as an epoxy resin. A resistor 17 is attached to the enlarged diameter and is potted in the resin with one lead being connected to terminal 18.

In assemblying the keep-alive cone of the present invention, insulator .13 is first positioned within the stepped cavities of cone 11 and the reduced diameter portion 14 of the center conductor is positioned in the bore of insulator 13. The large void surrounding a part of the enlarged diameter portion 16 is filled with powdered glass and the unit is then heated at 1050 degrees C. for about one and one-half minutes. The powdered glass is fused by the heating step and forms a rugged vacuum band between the center conductor and the cone 11. A series resistor 17 is next attached to the enlarged diameter portion 16 of the center conductor and resistor 17 and that part of the center conductor that protrudes above cone 11 are potted with a thermosetting resin, such as an epoxy resin.

It can thus be seen that the device described herein provides a keep-alive cone that is electrically stable, mechanically strong and will provide adequate protection to the detector crystals in a radar duplexer.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood, that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. The method of constructing a keep-alive cone comprising:

(a) first placing an insulator inside a cavity of a cone,

(b) then positioning one end of a center conductor in said insulator,

(c) then filling the remaining cavity of said cone with powdered glass,

((1) then heating said powdered glass whereby said glass is fused to said center conductor and said cone, and

(e) then potting the remaining portion of said center conductor with a thermosetting resin.

2. The method of constructing a keep-alive cone comprising:

(a) first placing an insulator inside a cavity of a cone,

([2) then positioning a reduced diameter portion of a center conductor in said insulator,

(c) then filling the remaining cavity of said cone with powdered glass,

(d) then heating said powdered glass whereby said glass is fused to said center conductor and said cone,

(e) then attaching a resistor to a portion of said center conductor extending beyond said cone, and

(1) then potting said resistor and said portion of said center conductor extending beyond said cone with a thermosetting resin.

3. The method of constructing a keep-alive cone comprising:

(a) first placing an insulator inside a cavity of a cone,

(b) then positioning a reduced diameter portion of a center conductor in said insulator,

(c) then filling the remaining cavity of said cone with powdered glass,

(d) then heating said powdered glass at a temperature of 1050 degrees C. for about one and one-half minutes whereby said glass is fused to said center conductor and said cone,

(e) then attaching a resistor to a portion of said center conductor extending beyond said cone, and

(1) then potting said resistor and said portion of said center conductor extending beyond said cone with an epoxy resin.

4. A keep-alive cone comprising:

(a) a cone having a stepped cavity,

(b) an insulator having a bore, said insulator being positioned at one end of said cavity,

(0) a center conductor having a reduced diameter .por-

tion and an enlarged diameter portion, said reduced diameter portion being positioned in said bore of said insulator and a part of said enlarged diameter portion being protruded above said cone,

(d) glass means securing said enlarged diameter portion to said cone, and

(e) a resin coating surrounding said part of said enlarged diameter portion protruding above said cone.

5. A keep-alive cone comprising:

(a) a housing having a conical outer surface and an internal cavity,

(b) an insulator having a bore, said insulator being positioned at one end of said cavity,

(0) a center conductor having a reduced diameter portion and an enlarged diameter portion, said reduced diameter portion being positioned in said bore of said insulator and a part of said enlarged diameter portion being protruded above said cone,

(d) glass means securing said enlarged diameter portion to said cone,

(e) a resistor attached to said enlarged diameter portion, and

(f) a resin coating surrounding said resistor and said part of said enlarged diameter portion protruding above said cone.

6. A keep-alive cone as set forth in claim 5 wherein said glass means securing said enlarged diameter portion to said cone comprises powdered glass that has been 15 heated to a fusing temperature.

No references cited. 

1. THE METHOD OF CONSTRUCTING A KEEP-ALIVE CONE COMPRISING: (A) FIRST PLACING AN INSULATOR INSIDE A CAVITY OF A CONE, (B) THEN POSITIONING ONE END OF A CENTER CONDUCTOR IN SAID INSULATOR, (C) THEN FILLING THE REMAINING CAVITY OF SAID CONE WITH POWDERED GLASS, (D) THEN HEATING SAID POWDERED GLASS WHEREBY SAID GLASS IS FUSED TO SAID CENTER CONDUCTOR AND SAID CONE, AND (E) THEN POTTING THE REMAINING PORTION OF SAID CENTER CONDUCTOR WITH A THERMOSETTING RESIN. 